Background: Patients with oral cancer are at higher risk of developing second primary esophageal cancer (SPEC) and the consensus for screening strategies remains unclear. This study aimed to examine comparative effectiveness and the stage-shift effect of endoscopic exam among patients with oral cancer.Method: A population-based longitudinal retrospective observational matched case and control cohort study with at least 5 years follow-up was conducted.We identified 45 457 newly diagnosed patients with oral cancer, 2004-2013, and the eligible patient with oral cancer was 39 401. Propensity score matching was used to match comparable groups, and the two groups (screening vs. nonscreening) was 5941, individually. The study primary endpoints were to compare detection of incident SPEC and the stage-shift effect of endoscopic screening between screened and nonscreened incident oral cancer patients.Cox proportional hazard and competing risk models were analyzed. Statistical analyses were conducted in 2020-2021.I-Chen Wu and Hui-Min Hsieh contributed equally to this study.

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